Originator: Bret Hazell, GeoTerra, Inc., President / Senior Project Manager
Publication_Date: 20160831
Title:
2015 Western Washington Regional Orthophotography - RGB with 2 Foot Pixel Resolution
Geospatial_Data_Presentation_Form: raster digital data
Description:
Abstract:
This data set contains 2 foot, 3-band (RGB), 8-bit/band color orthophotography that covers a large and mostly contiguous urban area in the Puget Sound area of western Washington. An orthophotograph is an aerial photograph that is geometrically corrected using a 3D terrain surface so that the scale is uniform and the image lacks distortion, allowing for highly accurate horizontal measurement of most ground-level features. Over 1,006 square miles of digital aerial imagery suitable for 2 foot orthophotography was acquired by GeoTerra, Inc. in the spring of 2015 for the purpose of updating regional base mapping data. The regional project was a collaborative effort between multiple agencies primarily within the Puget Sound region. King County oversaw the project and acted as lead manager for the effort on behalf of 88 participants. The aerial imagery was acquired using multiple, large-format digital mapping cameras. Overlapping stereo imagery was aerially-triangulated into large block adjustments using new and existing surveyed control. Existing terrain data was updated, or in some areas newly acquired, and used for rectifying the aerial imagery into digital orthophoto mosaics. These ortho image files are in a 3000' x 3000' contiguous, non-overlapping tile structure and are available in uncompressed GeoTIFF format. Each are projected to NAD 83/91(HARN), Western Washington State Plane North Zone, US Feet.
Purpose:
This data set was produced to provide (2.0 ft) pixel resolution, 8-bit depth, RGBIr orthophotography for the 2015 Western Washington Regional Aerial update, a multi-agency collaborative project.
(2.0 ft) pixel resolution orthoimagery for Western Washington, including parts of King, Snohomish, Skagit and Kitsap Counties
Status:
Progress: In work
Maintenance_and_Update_Frequency: None planned
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate: -123.075462
East_Bounding_Coordinate: -121.310773
North_Bounding_Coordinate: 48.330858
South_Bounding_Coordinate: 46.863750
Keywords:
Theme:
Theme_Keyword_Thesaurus: None
Theme_Keyword: natural color orthophotography
Theme_Keyword: orthos
Theme_Keyword: orthophotography
Theme_Keyword: aerial imagery
Theme_Keyword: RGB orthos
Theme_Keyword: 3-band imagery
Theme_Keyword: 8-bit imagery
Theme:
Theme_Keyword_Thesaurus: ISO 19115 Topic Categories
Theme_Keyword: imageryBaseMapsEarthCover
Place:
Place_Keyword_Thesaurus: None
Place_Keyword: King County
Place_Keyword: Washington
Place_Keyword: WA
Place_Keyword: Snohomish County
Place_Keyword: US
Place_Keyword: Kitsap County
Place_Keyword: Skagit County
Stratum:
Stratum_Keyword_Thesaurus: None
Stratum_Keyword: land
Temporal:
Temporal_Keyword_Thesaurus: None
Temporal_Keyword: Spring
Temporal_Keyword: leaf-off
Temporal_Keyword: 2015
Access_Constraints:
Access Constraints: Access to the digital files for the data from this project is limited to those participants who are listed in the contract between the county and GeoTerra, Inc. These participants signed a funding agreement with the county and paid a fee for the data they received. All participants are allowed to provide the data on public-facing websites to meet their internal business requirements. However, these public-facing sites cannot allow for download of the original data.
Use_Constraints:
Use Constraints: This orthophotographic data was acquired and produced by GeoTerra, Inc for the 2015 Washington Regional Aerials Update per contract agreement with King County, Washington for aerial image acquisition, orthophotographic processing and delivery. Data is only to be used by the county and participants specified in the 2015 contract which states in the Licensing Terms that the County and participants: 1) may distribute the data to all parties with whom they are currently contracted, and 2) may distribute the data to private individuals for non-commercial purposes only, Exceptions to this Licensing Term may exclude those 2015 participants that purchased full ownership of their respective data areas. Full ownership of all data acquired and produced for the 2015 contract is retained by GeoTerra.
Microsoft Windows 7 Version 6.1 (Build 7601) Service Pack 1; Esri ArcGIS 10.3.0.4322
Data_Quality_Information:
Attribute_Accuracy:
Attribute_Accuracy_Report: Raster data has no attribute table
Quantitative_Attribute_Accuracy_Assessment:
Attribute_Accuracy_Explanation: NA
Logical_Consistency_Report:
Tests for logical consistency indicate that image positions are consistent with earth coordinates covering the same area
Completeness_Report:
The data is complete and without gaps or zero pixel data for 100% of the required project area of 12-inch orthophotography.
Positional_Accuracy:
Horizontal_Positional_Accuracy:
Horizontal_Positional_Accuracy_Report:
Measurement of the horizontal (X and Y) accuracy of the rectified ortho imagery. Accuracy reports as well as other reports for the 2015 Aerials Project can be found at:
Horziontal accuracy of photo-identifiable features in the 12-inch orthophotography were measured and then compared with actual surveyed ground coordinates (QC checkpoints) to calculate statistical accuracy of the project. A 3rd party QC DAT Vendor (Miller Creek Aerial Mapping) peformed the QC analysis and determined that the 2015 project orthophotography meets or exceeds the horizontal acceptance criteria of RMSEr < 2.828 ft with a 95% confidence interval of < 4.896 ft.
Lineage:
Source_Information:
Source_Citation:
Citation_Information:
Publication_Date: 20150101
Title: idxp3000.shp
Type_of_Source_Media: None
Source_Citation_Abbreviation: idxp3000.shp
Source_Contribution:
3000' x 3000' tiling scheme in shp file format as provided by the King County technical manager to utilize for final ortho tile delivery.
Source_Information:
Source_Citation:
Citation_Information:
Publication_Date: 20150101
Title: Various
Type_of_Source_Media: None
Source_Citation_Abbreviation: Various
Source_Contribution:
New Survey Control was acquired by GeoTerra as needed to supplement the existing project ground control. All control, new and existing, was utilized to ensure the Aerial Triangulation block adjustment meets required accuracy standards.
Source_Information:
Source_Citation:
Citation_Information:
Publication_Date: 20150101
Title: Various names
Type_of_Source_Media: None
Source_Citation_Abbreviation: Various names
Source_Contribution:
All existing DEM data was provided in LAS, LAZ or ESRI Raster Grid format. Existing DEM data as provided for about 75% of the 12-inch ortho area consisted of older LiDAR data acquired between the years 2000-2003. Metadata for LiDAR during this time period cites an expected map accuracy of 1" = 2000', well beyond the 1" = 200' equivalent accuracy required for 12-inch orthos. The end-users (counties and other participants) decided that 2000-2003 LiDAR data would be used "as-is" to rectfiy the 12-inch orthos since no funds were available to acquire new, more accurate data. The remainder of the DEM data used for the 12-inch orthos, about 25% of the 12-inch ortho area, was from LiDAR acquired in the years 2013 and 2014. Metadata for these later years cites an accuracy that will will meet horizontal accuracy for rectifying 12-foot orthos.
Source_Information:
Source_Citation:
Citation_Information:
Publication_Date: 20150101
Title: Various names
Type_of_Source_Media: None
Source_Citation_Abbreviation: Various names
Source_Contribution:
Existing Survey Control data (in Excel and text format) as used for previous projects that fall within the 2015 procent extent. Control data was utilized in the Aerial Triangulation if still in existance or valid to ensure the resulting imagery was spatially accurate.
Process_Step:
Process_Description:
1. Flight Planning for 12-inch image acquistion occured in March of 2015 prior to flight. Multiple aerial flight vendors were subcontracted by GeoTerra to help ensure imagery was captured in a timely manner given seasonal weather and sun angle constraints. The project was broken into multiple blocks suitable for concurrent and multi-flight acquistion. All flights were planned and flown to acquire photos with a minimum 60% forward overlap and 30% sidelap. All 12-inch photos overlapped areas of 3-inch and 6-inch project photography along shared resolution boundaries to ensure proper coverage.
3. Acquisition of 4-band, 16 bit/band, digital aerial imagery at less than 0.9 ft pixel resolution using multiple Vexcel UltraCam aerial mapping cameras (Hawk, X, Xp and Eagle) during leaf-off and high sun-angle conditions. Each flight occured with AGPS and IMU. Enhanced areas of acquisition were acquired at higher image overlap and during a high sun-angle window to minimize buidling lean and shadows in identified dense urban areas. Post-flight, raw images were processed using propietary UltraMap software into full-histogram (unclipped) images in a final *.TIF format.
4. Update or correction of the existing Digital ElevationModel (DEM) to use for rectifying the images, specifiically for the year 2013-2014 LiDAR data (25% of the 12-inch ortho areas). All other areas (~75% of the 12-inch orthos) was used as-is, except for minor edits intended to reduce areas of extreme smearing caused by anomlies in the data. Stereo photography, as a product of the aerial triangulation, was used to update the point data in a 3D stereo environment.
5. The most nadir portion of every photo was identified by creating "seamlines" used to stitch the rectified images together. Seamlines were created using a combination of automatic and manual methods. Inpho's Ortho Master software was utilized to collect or manually adjust the seamlines polygons.
8. After initial Quality Assessment (QA) of the tiles by GeoTerra, additional QA was performed by Miller Creek Aerials Mapping (MCA). This evaluation was both quantitative and qualitative and was performed for a high percentage of tiles in each production zone, usually 50-75%,or greater, of the tiles. Calls were defined geographically and attributed as to type of issue and signficance. The RGB tiles were also evaluated by affected participants via a ArcGIS Online data portal maintained by GeoTerra. Combined calls, those from MCA and from the participants, were assembled. Review by GeoTerra and MCA, and when needed, by a working group of participants resulted in a final call list of issues that required repair. Upon completion of all fixes, the tiles went through final approval by GeoTerra and MCA prior to being delivered to King County. The county then distributed the data to each participant for their defined area of interest.
Process_Date: 20160401
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Miller Creek Aerials Mapping
Contact_Person: Jimmy Shultz
Contact_Address:
Address_Type: physical
Address: 19550 International Blvd, Ste 203
City: SeaTac
State_or_Province: WA
Postal_Code: 98188
Contact_Voice_Telephone: 26-402-6052
Process_Step:
Process_Description:
6. Rectification and mosaicing of all aerial photos using Inpho OrthoVista software, with the combined input of AT, updated DTM and seamlines.
7. Aerial Triagulation (AT) of all imagery acquired for 12-inch (1.0ft') pixel resolution orthos using processed Airborn GPS photo centers and new and existing surveyed ground control. Matching tie points and control were acquired from the 3-inch and 6-inch AT blocks and measured in the 12-inch blocks where appropriate to ensure an accurate match along resolution boundaries.
Distribution Liability: This data was produced under a contract between GeoTerra, Inc and King County. Data may be distributed by the county and the other participants only as specified in the 2015 contract which states the Licensing Terms for the county and the other participants. Licensed participants may distribute the data only to other parties to who they are currently contracted and to private individuals for non-commercial purposes only. Certain participants are exceptions to the licensing terms (i.e., full ownership) and are not restricted in the data's distribution.